Such a coupling head housing has been known from German Patent No. DE 662,874 and German Patent No. DE 29,26,301.
Accurate axial alignment between two central buffer couplings of two rail vehicles moving toward one another is not practically guaranteed under field conditions before the interlocking. This is due, on the one hand, to the condition of the track, and, on the other hand, to the condition of the vehicle. Therefore, vertical and lateral offsets, but also angular offsets are to be compensated prior to l;he coupling process. To specify an offset of two central buffer couplings, which deviates from the correct axial alignment and must not be exceeded if proper coupling is to be achieved, a so-called gripping range, within which a coupling process can still be initiated as intended and can be concluded after the adjustment to one another, is specified.
To increase the gripping range, German Patent No. DE 662,874 proposes, e.g., that a guide horn be arranged as a guide on the funnel side and that an inner strip be arranged as a second guide on the projecting centering projection. However, the hazard potential of a projecting guide horn is considered to be too high for certain vehicles, e.g., streetcars, because these vehicles are also operated in a flow of traffic.
The central buffer coupling disclosed in German Patent No. DE 29,26,301 has no guide horn on the coupling housing, and it has an inner guide surface on the centering projection to extend the gripping range. Based on its design, this coupling is specifically designed for railroad vehicles without limitations in terms of the dimensions.